This invention relates to inks for ink-jet printers, and, more particularly, to a process for increasing the solubility of carbon black in such inks.
Carbon black is a variable particle size material which is comprised basically of carbon, with variable attached functional groups. It is insoluble in all fluids, but will remain in suspension for extended periods of time in some fluids.
Carbon black is an indelible, very opaque printing material. It does not react with papers or copying machines. No photochemical decomposition occurs, and hence it is an acceptable archival printing material. Most ink-jet fluids do not meet these criteria.
Size-selected carbon olack is easy to purify to remove unwanted material; thus, it is superior to dyemolecule-based inks in this regard.
Although carbon black has several desirable properties that make it a prime candidate for ink compositions used in ink-jet printing, nevertheless, carbon black suspensions are easily susceptible to evaporation of the carrier fluid and readily precipitate out of the suspension. This propensity to precipitate limits the usefulness of carbon black in ink-jet fluids.